ELSEVIER Nuclear Instruments and Methods in Physics Research A 382 (1996) 140-146 INSTRUMENTS LMETnoos IN PHYSICS REsEAncH Sectron A First operations of the LNS heavy ions facility L. Calabretta”, G. Ciavola”, G. Cuttonea’*, S. Gammino”, P. Gmaj”, E. Migneco”, G. Raia”, D. Rifuggiato”, A. Rovelli”, J. Sura”, V. Scuderi”, E. Acerbib, F. Alessandriab, G. Bellomob, A. Bosottib, C. De Martinisb, D. Gioveb, P. Michelatob, C. Paganib, L. Rossib zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED “INFN-LNS V. le A. Doria 44/a, Catania, 95125, Italy ‘INFN-sezione di Milan0 and Universitci degli studi di Milano, Laboratorio LASA, Via F. lli Cervi 201, Segrate (Mi) 2oo90, Italy zyxwvutsrqpo Abstract A heavy ion facility is now available at Laboratorio Nazionale de1 Sud (LNS) of Catania. It can deliver beams with an energy up to 100 MeV/amu. The facility is based on a 15 MV HVEC tandem and a zyxwvutsrqponmlkjihgfedcbaZYXWVUTS K = 800 superconducting cyclotron as booster. During the last year, the facility came into operation. A 58Ni beam delivered by the tandem has been radially injected in the SC and then has been accelerated and extracted at 30 MeV/amu. In this paper the status of the facility together with the experience gained during the commissioning will be extensively reported. 1. Introduction A heavy ion facility designed at an energy up to 100 MeVlamu, is now operating at Laboratorio Nazionale de1 Sud (LNS) of Catania. The facility is based on two accelerators: a 15 MV HVEC tandem [ 1] and a K = 800 Superconducting Cyclotron (SC) which, in a first stage, will operate as booster. The SC project was conceived by the late Francesco Resmini and it has been developed in collaboration with the INFN-LASA group of Milan. Its features have been extensively reported in previous papers [2,3] so we now will recall the main milestones of the project. The SC was moved from Milan to LNS in 1990 after the first cool-down and the preliminary magnetic measurements done at LASA. In May 92, the cryostat was completed with all the radial penetrations, vacuum tested and reassembled inside the magnet yoke. Since November 1992, the coils have regularly been at the liquid helium temperature in order to allow excitation of the magnet and the final magnetic measurements. After these steps and the installation of the SC in its final configuration in May 94 the beam injection, acceleration and extraction test started and were successfully concluded on December 22nd of the same year with the extraction of a 30MeVlamu 58Ni beam. In June 95 this beam was available in the ex- perimental rooms and in July 95 the first nuclear physics experiment was successfully carried out. The layout of the accelerators facility is shown in Fig. 1 together with the experimental areas now available at LNS. In this paper we *Corresponding author. Fax +39 95 572 252, e-mail cuttone@lns.infn.it. will report the status of the main accelerators components and the experience gained during the final commissioning of the facility. 2. Tandem status The HVEC SMP tandem has been in operation since 1983. In 1986, after replacing the HVEC resistors with the new Vivrad resistors both for column and for the tubes, we obtained reliable running of the machine at 13 MV. In June 1988 a maximum operating voltage of 14 MV was reached after introducing a ‘37Cs radioactive source of 2 Ci. At this high gradient the belt lifetime decreased to about 1500 h, an unacceptably low value for normal operations. Consid- ering this problem and looking at the maximum voltage requested for the tandem to work as an injector for the SC we decided to realize in 1990 a full upgrading. We changed the charge system introducing the down-charge system and modifying the so-called “structure” around the belt from the old half-open shape with the spacers placed under the belt, to the new “triangular” shape with the spacers placed alternatively up and down around the belt. Moreover the forth and the fifth tubes were lengthened from 78 to 84 in. equal to all the others. The first tube was fully redesigned with a geometric length of 92 in. and an equivalent length of 84 in. and with a shortened straight circular section (all half value resistors) at the entrance followed by a 7” inclined electrode section to guarantee good electron suppression. We fully recalculated the beam optics in order to increase the transmission. Operational experience sup- 0168-9002/96/$15.00 Copyright 0 1996 Elsevier Science B.V. All rights reserved PII SO168-9002(96)00503-7